This is an updated version of my "MANAGING WALL TEXTURES" document that was
originally uploaded to alt.games.doom. This document is for PWAD builders
who wish to learn more about the use of wall, floor, and ceiling textures.
The function of the "unpegged" attribute is also discussed.

This is a well-written and concise description of how texture pegging and offsets work, from June 1994. So many levels from after June 1994 have texture errors; the only possible excuse is that the author wasn't on the internet. Even with ASCII drawings it is easy to follow.